SNAKES OF THE MESA VERDE NATIONAL PARK
by
Lewis T. Barry

There are to be found in the Mesa Verde the following snakes: Bull Snake (Pituophis sayi affinis), Smooth Green Snake (Liopeltis vernalis), Striped Racer (Masticophis taeniatus taeniatus), Prairie Rattlesnake (Crotalus confluentis confluentis), and the Rock Snake (Hypsiglena ochrorhynchus). These five species have been definitely recorded from this locality. Two additional snakes, Western Garter Snake (Thamnophis ordinoides vagrans) and the Western King or Milk Snake (Lampropeltis triangulum gentilis) have been found near Mesa Verde and should be found within the boundaries of the Park.

Bull Snake.

The Bull Snake may be recognized as the only large snake on the Mesa with tan or yellow ground color and dark brown or black blotches down the dorsal region. A Rock Snake might be mistaken for a small Bull Snake. The difference between those two species will be cited under the discussion of the Rock Snake.

The Bull Snake is non-poisonous and is probably as valuable to agriculture as any snake in Colorado as an active rodent control agent. His food consists largely of rats, mice, pocket gophers, spermophiles, etc. It is true that he is fond of eggs, but this is small pay for the number of rodents he eats. The Bull Snake swallows eggs whole and breaks them before they have reached the stomach by powerful contractions of the throat and upper body muscles.

This species kills its food by constriction. Usually the mouse or rat is caught and held in the mouth while the snake throws a coil around it with the upper part of the body. A constricition of this coil kills the victim.

The Bull Snake has a wonderful, if debatable, reputation as a killer of rattlesnakes. If one has actually witnessed this performance there is, of course, no doubt about it. Such a procedure seems unnatural to a Bull Snake as this species is not cannibalistic and there are few creatures that kill for the love of killing. The Reptile Book, by Raymond L. Ditmars, does not mention the killing of the Rattlesnakes in his discussion of the Bull Snake.

This species is often called the Blow Snake because of the loud hissing noise it makes when angry. A fold of skin in front of the air passage produces this noise.

The Bull Snake is oviparous and sometimes lays as many as fifteen eggs almost as large as those of a hen.

SMOOTH GREEN SNAKE

The Smooth Green Snake is very easily identified by the fact that it is the only Colorado Snake whose color is a bright grass green. The species has always been considered rare in Colorado, but work on the reptiles of this state is proving that they are common locally. Park Naturalist, Paul R. Franke, has the fourth state record of the Smooth Green Snake in the Park Museum. Mr. Franke has reported that additional specimens have been seen near Far View House.

This species is not poisonous, usually very gentle and may be handled without fear of being bitten. It is a snake to be valued as an aid to mankind, not as the Bull Snake is to be valued and protected as a rodent eater, but as an eater of injurious insects. The Smooth Green Snake has the distinction of being one of the few insect eating species, feeding upon grasshoppers, crickets and the larvae of moths and butterflies.

This species is oviparous, laying from four to eight eggs about one inch in length.

WESTERN STRIPED RACER

The only smooth scaled snake in Mesa Verde with a tan or greenish tan ground color and stripes running lengthwise is the Western Striped Racer. This snake is very long and slender. A four foot specimen may not be more than three-fourths of an inch in diameter at the thickest point.

Like the Bull Snake this species is valuable as a rodent eater. It has been found to be cannibalistic at times and also has been known to eat birds eggs. This snake does not kill rodents by constriction of its coils, but by squeezing them in its powerful jaws and pressing them into the ground at the same time.

The Western Striped Racer is very hard to capture owing to its remarkable speed and its ability to climb into trees and bushes with great rapidity, where its color makes it almost invisible. Though not poisonous this snake, when captured, will strike repeatedly, easily puncturing the skin with its needle-like teeth.

The Racers are all oviparous.

ROCK SNAKE

The Rock Snake is gray or light tan in color with dark brown blotches on the back. This sounds very much like the description of the Bull Snake, but the fact that the Rock Snake seldom exceeds seventeen inches in length while the Bull Snake may easily attain a length of five or six feet and the fact that the pupil of the eye of the Rock Snake is vertically elliptical while that of the Bull Snake is round, makes it impossible to confuse the two species.

This species is very rare in Colorado. Credit for the two specimens which have been found in the State goes to Ranger-Historian Don Watson of Mesa Verde National Park. Both specimens were found within the Park boundaries.

As the Rock Snake is known to eat lizards and birds eggs it is of doubtful economic value. The first specimen found by Mr. Watson had been run-over by a car and the exposed stomach showed that a a small specimen of the Sage Brush Swift (Sceloporus graciosus graciosus) had been eaten recently.

These snakes are almost entirely nocturnal and because of this may be much more common on the Mesa than would appear.

Prairie Rattlesnake

The only poisonous snake to be found in the Mesa Verde is the Rattlesnake. He is usually gray in color with darker markings or blotches on the back. The broad, triangular head and the presence of rattles or a button make identification simple.

It is often supposed that a Rattler's age may be determined by the number of rattles. However, as this snake gets new rattles every time it sheds its skin and it may shed its skin one to three times each year it is easily seen that the age may not be figured in this manner.

Though the Rattlesnake is deadly to man or beast, it is one of the most valuable snakes as a rodent eater. Almost the entire bill of fare of this snake consists of rats, mice, spermophiles, pocket gophers, kangaroo rats and other injurious rodents. Food is killed by an injection of venom and is swallowed whole after death which, in the case of mice, occurs in about eleven seconds.

It is well to remember that there are no medical records in Colorado of an adult human having been killed by the Prairies Rattlesnake. The only record of the giant, Crotalus atrox, the Western Diamond Backed Rattlesnake in Colorado is base upon one specimen which cannot be found at the present time. The Prairie Rattler seldom exceeds forty inches in length.

The fact that this snake is small should not make one lax in treating its bite. A physician should be reached at once. A ligature above the wound, that is, between the wound and the heart, and sucking are helpful until proper treatment can be reached. One with tender gums, or breaks in the tissues of the mouth or stomach should never suck the bite. Anti venom serums may be obtained at drug stores and are the best form of treatment.

Rattlesnakes bear from seven to twelve fully developed young which are ready at birth to care for themselves.